Hi,
In the short term, there's no alternative but to use the non-CUDA version
of VMD on versions of MacOS that require the latest CUDA versions.
When Apple force developers to change from Carbon to Cocoa for 64-bit
apps, this created problems for apps like VMD that depend on cross-platform
GUI toolkits such as FLTK and Tk, since they had to be completely rewritten
for Cocoa. Apple used to be directly involved in maintaining the MacOS X
ports of Tk, but that ended when their corporate policy went against
cross-platform GUI toolkits in favor of 100% native apps. When VMD 1.9.1
was released, I put a lot of effort into testing various bleeding edge
versions of FLTK and Tk to see if we could make a 64-bit VMD build that
was stable, but those tests showed that there were a number of problems
with the Cocoa versions of these tookits, and as a result we stuck with
the 32-bit VMD builds for production releases. I haven't tested the
latest FLTK/Tk toolkit versions to determine if the previous problems
with Cocoa GUI toolkits have been resolved or not, but I will be doing
so before VMD 1.9.2 is finalized. If the GUI toolkits have become
stable on 64-bit MacOS, then we will be able to compile VMD 1.9.2
with the latest revs of CUDA required for Yosemite and later MacOS versions.

I'll have more to say on this in a few more weeks, but for the time being
the best short-term plan is to use the non-CUDA binaries until I have
a better option.